Integrated circuits (ICs) have become increasingly important. Applications using ICs, such as cell phones, smartphones, tablets, laptops, notebook computers, PDAs, wireless email terminals, MP3 audio and video players, portable wireless web browsers and the like, are used by millions of people. Integrated circuits increasingly include powerful and efficient on-board data storage and logic circuitry for signal control and processing. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometric size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling-down process generally provides benefits by increasing production efficiency and lowering the associated costs.
Various semiconductor processes have been used for manufacturing integrated circuits, and different pattern densities might be required for the semiconductor processes (especially the exposure manufacturing processes). Although existing exposure techniques have been generally adequate for their intended purposes, they have not been entirely satisfactory in when it comes to uniformly assessing exposure issues for advanced technology nodes.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.